Had the same issue loading for my 300WSM. The Winchester primers almost fell into the primer pocket. They were also shorter and allowed for the primer to be set in about .030" further into the pocket.
For those that are thinking that my brass was stretched from a hot load or excessive use.... think again! This was on NEW Winchester brass! You would think that by using Winchester brass and their primers I wouldn't have an issue.
Same brass using CCI primers... no problems.

Win brass has had very shallow pockets the last few years. It doesn't surprise me that they are making their primers a bit short.
I'm wondering if win hasn't had some QC issues lately as my wlr and wlrm primers are a few years old. As I said earlier, I've shot thousands of loads with win primers,and not one issue.
I usually stay away from CCI if I can. They are simply the dirtiest burning primer out there. Fed, win, and rem are better in that regard.

Had a few primers after fully loaded fall right out of pockets these cartridges.Instead of trying to reuse primers that fell out I popped in some federal 210 that I still had. These primers went in with nice consistent tension and seating nice and flush.

Hunter
If I read that post right, you seated primers in fully loaded shells. You might as well have been playing Russian Roulette. I don't know how long you've been reloading, but I've been doing it for over forty years. In that time I've loaded hundreds of thousands of rounds. Out of that number I've had about a dozen primers fire when I was seating them. Scared the devil out of me every time. I dread to think what would have happened if any of the shells had been loaded.

__________________ WHEN YOU HUNT LONG RANGE, SOME TIMES THE SHOT IS THE TROPHY.

Hunter
If I read that post right, you seated primers in fully loaded shells. You might as well have been playing Russian Roulette. I don't know how long you've been reloading, but I've been doing it for over forty years. In that time I've loaded hundreds of thousands of rounds. Out of that number I've had about a dozen primers fire when I was seating them. Scared the devil out of me every time. I dread to think what would have happened if any of the shells had been loaded.

I've been loading 20 years and never had one go off seating in all the thousands I've loaded. I seat using the seater on my rock- chucker.

That said, you are foolish to the extreme if you don't yank the pill and dump the powder back into your scale's pan until you get another primer in there.

Good catch Nimrodmar10---- I'm hoping he was simply wording poorly and not re-priming loaded ammo.

I have experienced this issue with the WLR, and WLRM primers as well. When I first experienced it, it costed me about twenty pieces of Norma brass. I was shooting another brand of primers, ran out, and decided to try the WLR 's. I noticed the loose seat, and discarded them after firing.
It's a shame too, because they are very consistent too. One thing about Winchester primers, is that the WLR primers are the hottest STANDARD primer, and the WLRM I am told, are SLIGHTLY hotter than the 215.
BTW, I HIGHLY recommend that you do not re seat primers into a loaded case. If you so much as get a chard of metal or something on the seater plug, and you push in a primer......, well, you know the rest. I'd even venture ti say you won't do that again!

The problem with the WLR, WLRM is not a new problem either. They did that to me twenty years ago. Some brass seems to be a little better, but overall, and in general, they do fit looser.

__________________
AIM SMALL,MISS SMALL. 7 STW
LIFE IS TOO SHORT! AND WE ARE A LONG TIME DEAD!!!

Hunter
If I read that post right, you seated primers in fully loaded shells. You might as well have been playing Russian Roulette. I don't know how long you've been reloading, but I've been doing it for over forty years. In that time I've loaded hundreds of thousands of rounds. Out of that number I've had about a dozen primers fire when I was seating them. Scared the devil out of me every time. I dread to think what would have happened if any of the shells had been loaded.

+1, what he said!!!!

__________________
AIM SMALL,MISS SMALL. 7 STW
LIFE IS TOO SHORT! AND WE ARE A LONG TIME DEAD!!!